node-red-contrib-edge-trigger

Installation

npm install node-red-contrib-edge-trigger

Overview

The nodes in this package compare the numeric value of the incoming message
payload to the value of the previous message. If that value has crossed a
specified threshold in a specified direction, the message is forwarded.

Nodes

Falling edge

Given a threshold value, this node will forward its incoming message if the
numeric value of its payload has dropped below the threshold. Example
applications include turning on a heater when a temperature value drops.

Rising edge

Given a threshold value, this node will forward its incoming message if the
numeric value of its payload has increased above the threshold. Example
applications include turning on a cooler when a temperature value rises.

Hysteresis

This node combines the functions of the falling- and rising-edge nodes. It has
both rising and falling thresholds, and forwards the incoming message if its
value crosses either threshold in the appropriate direction. The outgoing
message has its edge property set to rising or falling.

This is useful in a situation where it would not be desirable to toggle an
output repeatedly on and off if a value hovers around a single threshold. For
example, a light that's activated by a luminosity sensor: it may be appropriate
to turn the light on when the sensor indicates 30 lux, but not to turn it off
again until the sensor indicates 40 lux.